• To compare change in body weight in non-diabetic, obese patients with and without impaired glucose tolerance and/or impaired fasting glucose with twice daily exenatide plus lifestyle modification plan or placebo plus lifestyle modification plan [ Time Frame: 24 weeks ] [ Designated as safety issue: No ]
  

• To compare the placebo and exenatide treatment groups on the change in: *Body Mass Index (BMI) *Waist circumference and hip circumference *Proportion of patients experiencing >=5% weight loss *Various pharmacodynamic measurements [ Time Frame: 24 weeks ] [ Designated as safety issue: No ]
  
• *Beta cell function and insulin sensitivity *Proportion of patients that demonstrate overt signs of diabetes diagnosis or normalization of impaired fasting glucose and/or impaired glucose tolerance *Safety and tolerability *Health outcome measures [ Time Frame: 24 weeks ] [ Designated as safety issue: No ]
  

Inclusion Criteria:

• Have a Body Mass Index (BMI) >= 30kg/m^2

Exclusion Criteria:

• Have ever participated in this study previously, or any other study using exenatide (AC2993/LY2148568) or GLP-1 analogs
• Have participated in an interventional medical, surgical, or pharmaceutical study (a study in which an experimental, drug, medical, or surgical treatment was given) within 30 days of study start (this criterion includes drugs that have not received regulatory approval for any indication at the time of study entry)
• Diagnosis of diabetes mellitus (other than gestational diabetes), or previous use of anti-diabetic medications for > 3 months
• Have had a change in prescribed lipid-lowering or blood pressure agents within 4 weeks of screening
• Used drugs for weight loss (e.g., Xenical [orlistat], Meridia [sibutramine], Acutrim [phenylpropanolamine], Accomplia [rimonabant], Alli [low-dose orlistat], or other similar over-the-counter weight loss remedies or medications) within 3 months of screening
• Are actively participating in, or have participated in a formal weight loss program within the last 3 months
• Have a history of chronic use of drugs that directly affect gastrointestinal motility, including, but not limited to Reglan (metoclopramide) and chronic macrolide antibiotics
• Have been treated with any anti-diabetic medications within 3 months of screening
• Are receiving chronic (lasting longer than 2 weeks) systemic glucocorticoid therapy or have received such therapy within the 4 weeks immediately prior to study start
• Have had bariatric surgery
• Have had an organ transplant